Some people have been asking about this lens.
I have just got mine, on dry tests on MDX series it shows the best port alignment with the front nodal point as:
Optical Dome Port; (I just have this one, but it should be exactly the same for the Compact Dome, and it has a big chance of being the same for the FE Dome Port)
SX Extension Ring AND
Extension Ring 40.
I will try to get some pool test done this week and will probably try it out on the sea later this month.